Try one of two things. First use metal from the ring if sizing down
or metal of the same formula when sizing up, ( Pt/Ir or Pt/Ru) as a
welding wire. Weld the rings instead of soldering and you should have
no seams at all.
Secondly, try the hard plumb platinum solder from PM West. Doesn’t
polish out or discolor. This platinum solder is actually made with
platinum unlike the platinum solders of old which had silver and
other stuff in them.
I have been using these two techniques for many years and never a
seam.
Damn! You Orchidians sure know alot. I thank you for all for the on
and off line responses. I quess I kind of posed a trick question. i
explained that i was not in My shop with the oxy-propane. I was in my
girlfriends shop with the old acetylene B bottle. She is a
silversmith. So i was sizing a ring for someone and used the lover
temp solder. i guess the majic bullet was to burnish the hell out of
it and stay away from a buffing wheel. So…the next time I am
far from my beloved Oxy-propane I will go to the home depot and get a
baby oxy and a baby propane bottle, hook it up to a mini torch,
strap a tank under each arm and hold the torch between my legs as I
fuse a piece of the same material into the seam. i will then scream
"I AM IRON… (that should read dork) Did you see the Movie yet? not
bad…one hell of a metalsmithing project.
I would like to officialy put this thread to rest. i will send out
the crab cake recipe to those who replied, off line.
*any one going to Vegas? I will be doing Demos for Foredom at the
Kassoy tool booth. stop by and heckel me please.
Wayne-- For sizings, try using a piece of jewelers platinum
(irid/plat or ruthenium/plat) rolled thin like solder, cut as big as
the cross section of the shank, rather than solder. Open your cut in
the shank slightly and place the chip of platinum so that both sides
of the cut are in full contact with the chip. Use a normal platinum
flame with your oxy-propane. Flux if you wish. With platinum, the
“soldering” technique is more like welding rather than “brazing”
which is what we do, so you may want to hit all sides of the joint
with the flame so that the chip is perfectly fused to the shank.
This metal will be closer in composition to the shank, and with your
skills with the torch and finishing tools, you just blend it right
in. This is the best way I know to make an invisible seam in a
platinum shank.
I’ve never tried this with a cobalt/platinum alloy.
I’ve used the plumb platinum solders available from PMWest for years
(since they came out) with good result (usual disclaimer here).
Contact Daniel (800) 999-PLAT to order.
If you’re going to weld, as Jim suggested, and it’s a heavy shank;
you won’t get a good joint unless you chamfer the ends of your shank
and use a somewhat oversize piece of thin platinum sheet (enough to
fill the chamfer). Use the same alloy as the ring. Pt/Co will turn
blue on you when you heat it. Also, every platinum reference I’ve
ever read insists flux will contaminate your joint; don’t use flux!
You don’t need it anyway.
If there are diamonds in the piece, you can apply boric acid in
alcohol just to the area with the stones and weld, that’ll protect
them from oxidizing somewhat. However, if diamonds are close to your
joint, even 1/3 of the way down the shank,you may overheat them
anyway. I wouldn’t take any other gemstone anywhere near the kind of
rapid heating platinum welding or plumb soldering requires. If there
are stones that are risky to heat find someone with a laser and job
it out.
I watched this thread w/o posting. Lots of good ideas and
techniques, but the occasional burning of melee, in sizing platinum
diamond bands where the melee are set more than 2/3 way round the
shank, is partially what finally pushed me into the laser. With the
laser I no longer ever use a torch on platinum. No seams, no burnt
stones, even retipping platinum settings without removing gemstones
is possible with very little risk of damage if you take precautions.
Even cobalt platinum is not too difficult to size with the laser